Concord is the most populous city in Contra Costa County, California, United States. According to an estimate completed by the United States Census Bureau, the city had a population of 123,261 in 2025, making it the tenth most populous city in the San Francisco Bay Area. Founded in 1869 as Todos Santos by Don Salvio Pacheco II, a noted Californio ranchero, the name was later changed to Concord. The city is a major regional suburban East Bay center within the San Francisco Bay Area, and is 29 miles east of San Francisco.